The present invention relates to an electrophotographic reproduction device utilizing an assembly of linear lens arrays to project a document image onto a photosensitive image plane; each lens array associated with a particular magnification characteristic. More particularly, the present invention relates to mechanical drive arrangements for placing the appropriate lens array into an optical imaging path following selection of the desired document magnification value.
Linear image transmitters used to transmit images of an object on an object plane to an image plane are known to the art in several forms. An array of lenslets formed vertically in a linear form and known as strip lenses are disclosed in U.S. Pat. No. 3,544,190. A plurality of optical light pipe fibers formed into a linear image transmitter is disclosed in U.S. Pat. No. 4,194,827. A third type of linear lens, one finding current usage in a number of reproduction devices, comprises a plurality of bundled gradient index optical fibers. As described in U.S. Pat. No. 3,658,407, a light conducting fiber made of glass or synthetic resin has a refractive index distribution in a cross-section thereof that varies parobolically outward from a center portion thereof. Each fiber acts as a focusing lens to transmit part of an image of an object placed near one end. An assembly of fibers, in a staggered two-row array, transmits and focuses an image of the object on an image plane. The fiber lenses are produced under the trade name "SELFOC"; the mark is registered in Japan and owned by Nippon Sheet Glass Co., Ltd.
In the above-identified linear image transmitting systems, the lens arrays disclosed form images at a photosensivite image plane at a magnification of 1:1. In at least the case of the gradient index lens configuration, a second lens array adapted to form reduced or enlarged images of the object at the image plane may be used in conjunction with the unity magnification lens, to enable a multi-magnification reproduction device. A gradient index lens capable of forming reduced or enlarged images at an image plane is disclosed in U.S. Pat. No. 4,331,380 assigned to the same assignee as the present invention. As disclosed therein a multi-magnification gradient index lens assembly is formed by combining two or more gradient index lens arrays, each array designed to form images transmitted therethrough at a specific magnification at the image plane. The positioning of the appropriate lens array in the optical path, and the rotation of the lens assembly to change the magnification from reduction to enlargement, is disclosed in general terms.
All of the above cited references are incorporated by reference herein for appropriate teachings of additional or alternative details, features and/or technical background.
The present invention is directed towards a preferred mechanical arrangement for accomplishing the positioning of one of a plurality of linear lens arrays in a multi-magnification reproduction system. More particularly, the invention relates to an imaging system for a multi-magnification electrophotographic reproduction device wherein a document on an object plane is reproduced on a photosensitive image plane at a selected magnification, said system comprising:
a first linear lens array positioned between the object and image plane, said first array adapted to transmit an image of said document onto said image plane at a first magnification,
at least a second linear lens array positioned between the object and image planes, said second lens array adapted to transmit an image of said document onto said image plane at a second magnification,
means for providing relative movement between document, lens array assembly and image plane for a selected magnification,
means for illuminating a narrow longitudinal strip of said document, and
means for providing lateral and rotational movement to said lens array assembly.